The invention relates to a surgical bone punch having a stationary shaft joined to a handgrip, a slide shaft mounted for longitudinal displacement on this stationary shaft, and a motorized drive in the handgrip for displacement of the slide shaft from a proximal inoperative position to a distal operative position with a preset forward displacement force.
Such a surgical bone punch with a pneumatic drive is known, for example, from DE 20 2004 015 643 U1. The pneumatic drive in the handgrip facilitates the work for the operator and results in reproducible forward displacement forces, which are characteristic of the handgrip, but, on the other hand, do not lend themselves to adaptation to differently dimensioned units consisting of stationary shaft and slide shaft. When such units consisting of stationary shaft and slide shaft, which are differently dimensioned, for example, have bone cutting edges of different width, are used, the cutting forces arising per unit of length of the bone cutting edge can, in the case of narrow cutting edges, therefore, become so great as to result in undesired damage to the cutting edges or undesired injury to the tissue.
In known bone punches, it is, therefore, provided that the forward displacement forces of the drive can be set, for example, by switching over to different intake valves for the pneumatic actuating medium in the handgrip. However, in particular, when exchanging the units consisting of stationary shaft and slide shaft, this is awkward for the operator, and there is the risk that the switching-over will be forgotten and that the bone punch will then be operated with a forward displacement force which is not appropriate for the respectively used unit consisting of stationary shaft and slide shaft.
The object of the invention is to so design a surgical bone punch of the kind described at the outset that the forward displacement force of a unit consisting of stationary shaft and slide shaft automatically adapts to the necessary size, without any change in the forward displacement force supplied by the motorized drive being necessary therefor.